1. Field of the Invention
This invention relates to high luminance color suppressing circuit for suppressing color signals when an image of an object having high luminance is photographed and the color signal is saturated.
2. Description of the Related Art
In a video camera, a CCD (charge coupled device) outputs a color signal the level of which corresponds to the luminance of an object. In photographing an object having high luminance, a state results in which the level (luminance) of the color signal is excessively high. When the level of the color signal is excessively high, so-called color signal saturation occurs. Color signal saturation means a situation in which the color of an object cannot be reproduced. Generally, a high luminance color suppressing circuit is mounted in a video camera. When a color signal is generated that corresponds to an object having high luminance at which color cannot be reproduced, the high luminance color suppressing circuit forcibly sets the color signal to, for example, white.
The level at which the color signal is saturated depends on each color signal. That is, the saturation level of a green color signal G is the lowest. Further, the saturation level becomes higher from the red color signal R to the blue color signal B. The high luminance color suppressing circuit suppresses the color signal and sets it to a value indicating, for example, white, when one of the respective color signals reaches the lowest saturation level, that is, the saturation level (saturation detection level Gdet) of the green color signal G.
An explanation will be given of the operation of a conventional high luminance color suppressing circuit with reference to FIG. 5. FIG. 5 illustrates waveform diagrams showing the operation of a conventional high luminance color suppressing circuit. In FIG. 5, the axis of ordinates (vertical axis) designates a level of a color signal outputted from the high luminance color suppressing circuit, and the axis of abscissa (horizontal axis) designates a level of luminance of an object. The levels of the red color signal Rout, the green color signal Gout and the blue color signal Bout (red, green, blue color signals Rin, Gin and Bin) shown in FIG. 5 signifies a case in which an image of a reddish object, for example, an object having "skin color" is photographed. The level of the red color signal Rout (Rin) is higher than those of the green and blue color signals Gout and Bout (Gin, Bin). When the luminance of the object is enhanced, firstly, the red color signal Rout (Rin) reaches the saturation detection level Gdet (luminance I.sub.0), and thereafter, the respective color signals are forcibly set to a content indicating white (Rout=Gout=Bout=Gdet). Thus, for luminance levels less than I.sub.0, the colors are reproduced, while for luminance levels exceeding I.sub.0, a white color is shown.